1. Field of the Invention
The present invention relates to a remote position designation system, and more particularly to a remote position designation system including a transmitter unit adapted to transmit signals of the same frequency, but having different phases, and a receiver unit adapted to receive those signals from the transmitter unit to process them.
2. Description of the Prior Art
Generally, a remote position designation system is applied to a variety of electronic appliances such as TVs, computers, VCRs, LDPs, DVD players, VOD systems, cable TV terminals, communication terminals, video game machines for home use, and computers for toddlers. Such a remote position designation system includes a transmitter unit and a receiver unit. The transmitter unit transmits signals to the receiver unit equipped in an electronic appliance spaced apart from the transmitter unit by a certain distance, using two or more transmitters, respectively. The receiver unit amplifies the signals received thereto in accordance with an amplification method using amplifier circuits or an optical amplification method. The amplified signals are then processed by an analog/digital conversion process. Thereafter, a difference between the converted signals is calculated and then converted into a corresponding value on a coordinate system. In the case in which it is difficult for the remote position designation system to distinguish the signals simultaneously received thereto, the transmitter device transmits those signals at a certain interval of time, respectively, in order to allow the receiver unit to process the signals distinguishable from each other. For this reason, the above mentioned conventional remote position designation system involves an increase in costs in that it is necessary to use very complex circuits requiring a high optical accuracy for processing of received signals. In order to achieve an improvement in accuracy, DC signals, which can be processed using a relatively easy signal processing, are used as transmitting signals. However, it is difficult for such DC signals to be distinguished from peripheral noise, so that use of DC signals may not provide an enhanced position designation accuracy. For this reason, this method is impractical.
The signal processing method used in the above mentioned remote position designation system cannot directly process signals transmitted from any of the existing transmitters. For this reason, it is difficult to simplify the configuration of the remote position designation system. Furthermore, the essential signal processing directly associated with the position designation accuracy is carried out using bulky analog circuits. For this reason, it is difficult to miniaturize the remote position designation system. In addition, it is impossible to reduce the costs.
Therefore, an object of the invention is to provide a remote position designation system capable of processing signals transmitted from a transmitter unit in a digital fashion by a receiver unit, thereby achieving an easy selection of a desired function from a menu displayed on the screen of an electronic appliance to which the remote position designation system is applied.
In accordance with the present invention, this object is accomplished by providing a remote position designation system for designating an optional position on a plane at a place remote from the plane comprising: a transmitter unit including transmitters adapted to transmit, as a position signal, signals of the same frequency, but having different phases, in a simultaneous fashion, respectively; a receiver unit for receiving the signals transmitted from the transmitters of the transmitter unit in the form of a composite signal, amplifying the received composite signal to a saturation level, and conducting a signal processing for the amplified signal to obtain position information associated with a phase shift of the amplified signal from a reference phase; and a control unit for generating a control signal adapted to display a position designated by the position signal from the transmitter unit on a screen, based on the position information from the receiver unit.
The remote position designation system of the present invention is applicable to a variety of electronic appliances such as TVs, computers, VCRs, LDPs, DVD players, VOD systems, cable TV terminals, communication terminals, video game machines for home use, and computers for toddlers. In this case, an easy movement of a curser can be achieved.